Compile for Java8 by default

[martinbonnin]

If not, the Kotlin compiler will use the version of the JAVA_HOME jdk.

[benasher44]

@martinbonnin this configuration is intentionally omitted. See #31

[martinbonnin]

I'm not sure this is the same problem. When bumping Gradle and Kotlin, the bytecode produced depends on the host Java:

mbonnin:~/git/uuid$ java --version  
openjdk 19.0.2 2023-01-17
OpenJDK Runtime Environment Zulu19.32+13-CA (build 19.0.2+7)
OpenJDK 64-Bit Server VM Zulu19.32+13-CA (build 19.0.2+7, mixed mode, sharing)

mbonnin:~/git/uuid$ ./gradlew jvmJar
[...]
BUILD SUCCESSFUL in 817ms
2 actionable tasks: 2 executed

mbonnin:~/git/uuid$ file build/classes/kotlin/jvm/main/com/benasher44/uuid/UuidHasher.class
build/classes/kotlin/jvm/main/com/benasher44/uuid/UuidHasher.class: compiled Java class data, version 63.0

This fails down the road when trying to use the lib:

Cannot inline bytecode built with JVM target 19 into bytecode that is being built with JVM target 1.8. Please specify proper '-jvm-target' option

So maybe it's a KGP thing or maybe it's a Gradle thing but in all cases, it shouldn't hurt to be explicit about Java8?

[benasher44]

Ah looks like I missed that Kotlin 1.8.0 dropped support for 1.6. This seems good then. Mind just moving this config to the "intentionally left blank" (replacing it)?